Oxaphosphiranes: isolable phosphorus-containing epoxide rings

Abstract

Combining different heteroatoms in an epoxide-type ring having Lewis basic and acidic characteristics is challenging as it creates an increasing number of polar bonds and high ring strain energy. The first examples of isolable oxaphosphiranes, i.e., epoxide rings with a phosphorus atom, have been synthesized using a facile and effective protocol starting from [pentacarbonyl{dichloro(trityl)phosphane}molybdenum(0)] (trityl = CPh₃), tert-butyllithium and commercially available fluorinated benzaldehydes. Reactions with various acids and bases will be described. Theoretical results unveil a singlet carbene-like FMO situation at phosphorus in oxaphosphirane, which is used to explain reaction mechanisms.